The present disclosure relates broadly to a system and method for managing distribution of vehicle power in a multiple battery system. As will be understood by those skilled in the art, the various exemplary embodiments and implementations described herein may have application to all types of vehicles, such as tractor/trailer combinations, recreational vehicles, agricultural tractors, and other light and heavy duty vehicles.
The trucking industry has traditionally used tractor/trailer combinations to transport cargo over roadways to intended destinations. The tractor and one or more trailers are mechanically coupled together, and electrically linked via wires and cables to supply power to numerous electrical subsystems located on the tractor and/or the trailer. Many electrical subsystems (or “auxiliary loads”) utilize electrical energy when the vehicle is running, and also utilize electrical energy provided by the vehicle's battery when the tractor engine is in an inactive or power-off condition. The crank battery supplies electrical power necessary to start the tractor's cranking system, and is charged by an alternator mechanically driven by the engine when running. In order to preserve sufficient cranking power, measures must generally be taken to avoid discharging the crank battery below a predetermined threshold voltage. The construction of the vehicle battery is well-known, and generally comprises a plurality of connected rechargeable lead-acid secondary cells.
In addition to various auxiliary loads powered by the tractor's electrical system, many modern tractor/trailer combinations have other integrated systems, such as electrically-powered liftgates, that have generally independent power sources. Liftgate batteries typically do not have their own charging system, and must therefore rely on power from the tractor or the reefer unit.